Two-way display-type liquid crystal display device

ABSTRACT

Disclosed is a two-way display-type liquid crystal display device. The device includes a pair of upper and lower display modules for displaying different information; a plurality of two-way light sources for simultaneously supplying predetermined amounts of light rays to the upper and lower display modules; a light guide panel separately located at a side of the two-way light sources in a manner such that the upper and lower display modules are positioned on upper and lower surfaces of the light guide panel, respectively, the light guide panel functioning to guide light rays radiated from the two-way light sources in two directions toward the upper and lower display modules; a scattering film interposed between the light guide panel and the lower display module, for scattering and reflecting the light rays radiated from the two-way light sources, toward the upper display module; and a reflective and transmissive sheet interposed between the light guide panel and the lower display module, for reflecting one part of the light rays radiated from the two-way light sources, toward the upper display module, and transmitting the other part of the light rays toward the lower display module.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a liquid crystal display device,and more particularly, the present invention relates to a two-waydisplay-type liquid crystal display device which enables light raysradiated from one light source to simultaneously contribute to operationof upper and lower display modules, thereby restraining the number oflight sources from being unnecessarily increased, and preventing aweight and a thickness thereof from being increased and assembly thereoffrom being complicated due to provision of an additional light source.

[0003] 2. Description of the Related Art

[0004] Recently, with the advent of the information era, importance of aliquid crystal display device as one of information display devices hasbeen increasingly emphasized.

[0005] Differently from other information display devices such as acathode ray tube (CRT), a plasma display panel (PDP), etc., since theliquid crystal display device renders numerous advantages in terms ofminiaturization, light weight, and low power consumption, it has beenwidely adopted and used in various information processing devices suchas a notebook computer, a desktop computer, a television, a mobilecommunication terminal, and so on.

[0006] Referring to FIG. 1, a conventional two-way display-type liquidcrystal display device 20, which is adopted in a conventionalinformation processing device, for example, a mobile communicationterminal, largely includes a light guide panel 23, upper and lowerdisplay modules 21 and 22 which are respectively positioned on an uppersurface and below a lower surface of the light guide panel 23, and aprinted circuit board 25 on which diverse circuit parts for driving theupper and lower display modules 21 and 22 are mounted.

[0007] A plurality of light source chips 24 are located at a side of thelight guide panel 23, and separately, a light source sheet 26 is locatedunder the printed circuit board 25. The light source chips 24 located atthe side of the light guide panel 23 function to supply light raystoward the upper display module 21, and the light source sheet 26located under the printed circuit board 25 functions to supply lightrays toward the lower display module 22.

[0008] As can be readily seen from FIG. 1, a reflective sheet 27 isinterposed between the light guide panel 23 and the printed circuitboard 25. The reflective sheet 27 reflects light rays radiated from thelight source chips 24 toward the upper display module 21 to prevent thelight rays from leaking in a direction opposite to the upper displaymodule 21. In this connection, it is the norm that the reflective sheet27 has a reflectance approaching 100% so as to maximize the lightcollection rate at the upper display module 21.

[0009] In addition to the reflective sheet 27, a plurality of reflectivedots (not shown) are formed on the lower surface of the light guidepanel 23. The reflective dots function to scatter and reflect light raysradiated from the light source chips 24 and light rays reflected fromthe reflective sheet 27 toward the upper display module 21 to therebyfurther improve the light collection rate at the upper display module21. Generally, each reflective dot has a size of no less than 20 μm.

[0010] In the above-described construction, the upper display module 21receives light rays radiated from the light source chips 24 by themedium of the light guide panel 23 and, using these light rays, displaysmain information of the information processing device, for example, incolors. The lower display module 22 directly receives light raysradiated from the light source sheet 26 and, using these light rays,displays simple auxiliary information of the information processingdevice, for example, in monochrome.

[0011] However, the conventional two-way display-type liquid crystaldisplay device 20 constructed as mentioned above suffers from defects asdescribed below.

[0012] First, since the upper and lower display modules 21 and 22respectively employ, as their light sources, the light source chips 24and the light source sheet 26, a thickness and a weight of the entireliquid crystal display device are increased due to a region additionallyoccupied by the light sources. Accordingly, it is difficult to maintaina quality of the liquid crystal display device above a predeterminedlevel.

[0013] That is to say, in the case that the upper and lower displaymodules 21 and 22 respectively employ different light sources, theliquid crystal display device should be equipped with separate drivingparts for driving the respective light sources, such as an inverter.Consequently, a thickness and a weight of the entire liquid displaydevice are increased, and assembly thereof is complicated.

[0014] Meanwhile, as described above, the upper display module 21displays, by using the light rays radiated from the light source chips24, main information of the information processing device, in colors, asthe case may be. In this color display mode, in order to ensure normaloperation of the upper display module 21, light rays having a brightnesswhich is 10 times greater than that of light rays in a monochromedisplay mode, are required.

[0015] However, since the light source chips 24, which contribute to abrightness of the upper display module 21, employ only the reflectivedots to increase the brightness of the light rays, unless a quality ofthe light source chips 24 is not remarkably improved, a brightnessrequirement under the color display mode cannot be properly met.Consequently, the conventional liquid crystal display device cannotaccomplish a display quality above a preselected level.

[0016] Moreover, because it is the norm that the conventional lightsource chips 24 are located at the only one side of the light guidepanel 23 in the above-described conventional liquid crystal displaydevice, one side end portion of the upper display module 21 which isdistant from the light source chips 24 becomes darker than the otherside end portion of the upper display module 21 which is close to thelight source chips 24. As a result, brightness distribution uniformityof the upper display module 21 is deteriorated.

[0017] Of course, to cope with this problem, light source chips can belocated at both sides of the light guide panel 23. However, in thiscase, a manufacturing cost of the liquid crystal display device isconsiderably increased, and a thickness and a weight of the entireliquid crystal display device are increased due to a region additionallyoccupied by the light source chips.

SUMMARY OF THE INVENTION

[0018] Accordingly, the present invention has been made in an effort tosolve the problems occurring in the related art, and an object of thepresent invention is to provide a two-way display-type liquid crystaldisplay device which has a part layout enabling light rays radiated fromone light source to simultaneously contribute to operation of upper andlower display modules, thereby restraining the number of light sourcesfrom being unnecessarily increased, and preventing a weight and athickness thereof from being increased and assembly thereof from beingcomplicated due to provision of an additional light source.

[0019] Another object of the present invention is to provide a two-waydisplay-type liquid crystal display device which has a separatestructure having an improved light scattering function when compared tothe conventional reflective dots, thereby increasing a brightness oflight rays radiated from a light source, meeting a requirement under acolor display mode and improving brightness distribution uniformity.

[0020] In order to achieve the above object, according to the presentinvention, there is provided a two-way display-type liquid crystaldisplay device comprising: a pair of upper and lower display modules fordisplaying different information; a plurality of two-way light sourcesfor simultaneously supplying predetermined amounts of light rays to theupper and lower display modules; a light guide panel separately locatedat a side of the two-way light sources in a manner such that the upperand lower display modules are positioned on upper and lower surfaces ofthe light guide panel, respectively, the light guide panel functioningto guide light rays radiated from the two-way light sources in twodirections toward the upper and lower display modules; a scattering filminterposed between the light guide panel and the lower display module,for scattering and reflecting the light rays radiated from the two-waylight sources toward the upper display module; and a reflective andtransmissive sheet interposed between the light guide panel and thelower display module, for reflecting one part of the light rays radiatedfrom the two-way light sources toward the upper display module andtransmitting the other part of the light rays toward the lower displaymodule.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above objects, and other features and advantages of thepresent invention will become more apparent after a reading of thefollowing detailed description when taken in conjunction with thedrawings, in which:

[0022]FIG. 1 is a perspective view illustrating a conventional two-waydisplay-type liquid crystal display device;

[0023]FIG. 2 is a perspective view illustrating a two-way display-typeliquid crystal display device in accordance with a first embodiment ofthe present invention;

[0024]FIG. 3 is a partially-exploded upside-down view of the two-waydisplay-type liquid crystal display device according to the firstembodiment of the present invention;

[0025]FIG. 4 is a perspective view illustrating a two-way display-typeliquid crystal display device in accordance with a second embodiment ofthe present invention;

[0026]FIG. 5 is a partially-exploded upside-down view illustrating atwo-way display-type liquid crystal display device in accordance with athird embodiment of the present invention; and

[0027]FIG. 6 is a partially-exploded upside-down view illustrating atwo-way display-type liquid crystal display device in accordance with afourth embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0028] Reference will now be made in greater detail to a preferredembodiment of the invention, an example of which is illustrated in theaccompanying drawings. Wherever possible, the same reference numeralswill be used throughout the drawings and the description to refer to thesame or like parts.

[0029] As shown in FIG. 2, a two-way display-type liquid crystal displaydevice 10 in accordance with a first embodiment of the present inventionlargely includes a plurality of two-way light sources 6; a light guidepanel 3 which is separately located at a side of the two-way lightsources 6; upper and lower display modules 1 and 2 which arerespectively positioned on upper and lower surfaces of the light guidepanel 3; and a printed circuit board 7 on which diverse circuit partsfor driving the upper and lower display modules 1 and 2 are mounted. Ascan be readily seen from FIG. 2, the upper and lower display module 1and 2 respectively rest on the upper and lower surfaces of the lightguide panel 3.

[0030] The two-way light sources 6 function to simultaneously supplypredetermined amounts of light rays to the upper and lower displaymodules 1 and 2. The light guide panel 3 guides the light rays radiatedfrom the two-way light sources 6 in two directions toward the upper andlower display modules 1 and 2.

[0031] The upper display module 1 receives one part of the light raysradiated from the two-way light sources 6 by the medium of the lightguide panel 3 and, using these light rays, displays main information ofthe information processing device to which the upper display module 1belongs. The lower display module 2 receives the other part of the lightrays radiated from the two-way light sources 6, which leaks through thelower surface of the light guide panel 3 and, using these light rays,displays simple auxiliary information of the information processingdevice to which the lower display module 2 belongs.

[0032] In the case that a color filter (not shown) is provided for theupper or lower display module 1 or 2, the corresponding display module 1or 2 can display the corresponding information in colors.

[0033] Due to the fact that the upper display module 1 displays the maininformation of the information processing device, it is the norm thatthe upper display module 1 has the color filter to be operated under acolor display mode. Also, due to the fact that the lower display module2 displays the simple auxiliary information of the informationprocessing device, it is the norm that the lower display module 2 isoperated under a monochrome display mode without any costly colorfilter. Of course, as the case may be, the display modes of the upperand lower display modules 1 and 2 can be changed with each other.

[0034] When one of the upper and lower display modules 1 and 2 isoperated under the color display mode, the light rays radiated from thetwo-way light sources 6 may be white light, which is advantageous torealization of colors.

[0035] Here, as shown in FIG. 2, a reflective and transmissive sheet 5is interposed between the light guide panel 3 and the lower displaymodule 2. The reflective and transmissive sheet 5 functions to reflectone part, for example, 90% of the light rays radiated from the two-waylight sources 6 toward the upper display module 1, and transmit theother part, for example, 10% of the light rays toward the lower displaymodule 2.

[0036] By the function of the reflective and transmissive sheet 5, theupper and lower display modules 1 and 2 can properly implement theirinformation displaying procedures while commonly having the two-waylight sources 6 as single light source means without requiring separatededicated light sources as in the conventional art.

[0037] That is to say, in the conventional art, as aforementioned above,the reflective sheet interposed between the light guide panel and theprinted circuit board has a reflectance approaching 100% so as tomaximize a light collection rate at the upper display module. Thus, thelight rays radiated from a main light source can only be reflectedtoward the upper display module and cannot be transmitted toward thelower display module. By this fact, the lower display module must beprovided with a separate light source such as the light source sheet,whereby a thickness and a weight of the finally manufactured liquidcrystal display device are increased and assembly thereof iscomplicated.

[0038] However, in the present invention, the reflective andtransmissive sheet 5 is provided in place of the conventional reflectivesheet. As described above, the reflective and transmissive sheet 5reflects one part, for example, 90% of the light rays radiated from thetwo-way light sources 6 toward the upper display module 1, and transmitsthe other part, for example, 10% of the light rays toward the lowerdisplay module 2. Therefore, the light rays radiated from the two-waylight sources 6 can widely influences both of the upper and lowerdisplay modules 1 and 2. Consequently, differently from the conventionalart, the lower display module 2 can properly implement the informationdisplaying procedure without requiring a separate light source.

[0039] In the two-way display-type liquid crystal display device 10according to the present invention, since a part layout enabling thelight rays radiated from one light source to simultaneously contributeto operation of the upper and lower display modules 1 and 2 is attained,the number of light sources is restrained from being unnecessarilyincreased, a weight and a thickness of the liquid crystal display device10 are prevented from being increased, and assembly thereof is preventedfrom being complicated.

[0040] In the above-described construction, if separate measures are nottaken, the upper display module 1 cannot but receive a reduced amount oflight rays when compared to the conventional art. The reason for this isthat, while the conventional reflective sheet reflects nearly 100% ofthe light rays radiated from the light source toward the upper displaymodule, the present reflective and transmissive sheet 5 reflects only90% of the light rays radiated from the two-way light sources 6 towardthe upper display module 1.

[0041] In consideration of this fact, in the present invention, as shownin FIG. 2, a scattering film 4 is interposed between the light guidepanel 3 and the lower display module 2, preferably between the lightguide panel 3 and the reflective and transmissive sheet 5 to scatter andreflect the light rays radiated from the two-way light sources 6 towardthe upper display module 1. Accordingly, a short amount of light rays tobe supplied toward the upper display module 1 can be properlycompensated.

[0042] A plurality of scattering lines 4 a are formed on a surface ofthe scattering film 4 to linearly scatter the light rays radiated fromthe two-way light sources 6. The scattering lines 4 a may be randomly orregularly arranged one with another.

[0043] In this case, the scattering lines 4 a are projectedly formed tohave a fine line width in the range of 0.5˜5.5 μm, differently from theconventional reflective dots, to thereby form an elongate mountstructure. Therefore, when compared to the case of using theconventional reflective dots, it is possible to uniformly and distantlyscatter and reflect an increased amount of the light rays radiated fromthe two-way light sources 6 toward the upper display module 1. As aconsequence, even though the upper display module 1 receives the reducedamount of light rays under the influence of the reflective andtransmissive sheet 5, the upper display module 1 can properly implementits information displaying procedure since the short amount of lightrays is compensated by the function of the scattering film 4.

[0044] It is to be noted that each scattering line 4 a may be formed insuch a way as to define a contour of an irregular curve, a straight lineor a combination thereof.

[0045] Also, with a view of ensuring brightness distribution uniformityon the upper display module 1, the scattering lines 4 a may be formed ina manner such that they have a low density as the scattering lines 4 aare close to the light sources 6, and they have a high density as thescattering lines 4 a are away from the light sources 6. It is to beappreciated that a contour and an arrangement pattern of the scatteringlines 4 a may be varied as occasion demands.

[0046] Hence, the scattering lines 4 a adopted in the present inventionnot only perform a light ray compensating function, but also cooperatewith the two-way light sources 6 so as to improve a brightness of theupper display module 1 and ensure brightness distribution uniformity onthe upper display module 1.

[0047] As described above, by the fact that the scattering lines 4 a areprojectedly formed on the scattering film 4 to have the fine line widthin the range of 0.5˜5.5 μm, differently from the conventional reflectivedots, to thereby form the elongate mount structure, the scattering lines4 a perform the function of uniformly and distantly scattering andreflecting an increased amount of light rays toward the upper displaymodule 1 when compared to the case of using the conventional reflectivedots. Thus, due to the provision of the scattering lines 4 a, the upperdisplay module 1 is significantly improved in its brightness whencompared to the case of using the conventional reflective dots.

[0048] Therefore, in the present invention, by employing the scatteringfilm 4 which cooperates with the two-way light sources 6, it is possibleto increase a brightness and improve brightness distribution uniformityof the light rays supplied toward the upper display module 1, andthereby, a brightness requirement and a brightness distributionuniformity requirement under the color display mode can be properly met.

[0049] The scattering film 4 can be lightly placed on the lower surfaceof the light guide panel 3 by an insert molding process, or can beforcibly attached to the lower surface of the light guide panel 3 by apress molding process. It is to be appreciated that the scattering film4 may be positioned on the lower surface of the light guide panel 3 in avariety of ways depending upon a situation.

[0050] As can be readily seen from the drawings, an accommodating groove3 a is formed on the lower surface of the light guide panel 3, on whichthe reflective and transmissive sheet 5 and the scattering film 4 arepositioned.

[0051] Due to the presence of the accommodating groove 3 a, a structurefor mechanically installing the reflective and transmissive sheet 5 andthe scattering film 4 can be stably reinforced. Thus, the reflective andtransmissive sheet 5 and the scattering film 4 can maintain a normalconfiguration for an extended period of time against external impact.

[0052] Meanwhile, in a second embodiment of the present invention asshown in FIG. 4, a plurality of, for example, one to three transparentdiffusion sheets 8 are interposed between the light guide panel 3 andthe upper display module 1 to diffuse the light rays radiated from thetwo-way light sources 6 toward the upper display module 1.

[0053] Grain of a micro dimension is formed on a surface of eachtransparent diffusion sheet 8. By the presence of the grain, thetransparent diffusion sheets 8 can scatter and diffuse, over a widearea, the light rays radiated from the two-way light sources 6 towardthe upper display module 1. Therefore, although the upper display module1 receives the reduced amount of light rays under the influence of thereflective and transmissive sheet 5, the short amount of light rays canbe compensated by the function of the scattering film 4 and thetransparent diffusion sheet 8, as a result of which the upper displaymodule 1 can properly implement its information displaying procedure.

[0054] In the meanwhile, in a third embodiment of the present inventionas shown in FIG. 5, a transparent color induction film 9 is interposedbetween the light guide panel 3 and the lower display module 2,preferably between the reflective and transmissive sheet 5 and the lowerdisplay module 2 to colorize the light rays radiated from the two-waylight sources 6.

[0055] As described above, the upper display module 1 of the presentinvention receives one part of the light rays radiated from the two-waylight sources 6 by the medium of the light guide panel 3 and, usingthese light rays, displays main information of the informationprocessing device to which the upper display module 1 belongs, forexample, in colors. In this color display mode, the two-way lightsources 6 usually radiate white rays which are advantageous torealization of colors.

[0056] In this color display mode, since the upper and lower displaymodules 1 and 2 of the present invention commonly possess the two-waylight sources 6 as single light source means, like the upper displaymodule 1, the lower display module 2 receives white rays. Unlessseparate measures such as a costly color filter are not provided, thelower display module 2 cannot but display the corresponding informationin monochrome.

[0057] In consideration of this fact, in the present invention, thetransparent color induction film 9 is interposed between the light guidepanel 3 and the lower display module 2, preferably between thereflective and transmissive sheet 5 and the lower display module 2. Bythe presence of the transparent color induction film 9, at the same timethat the light rays radiated from the two-way light sources 6 passthrough the transparent color induction film 9, they can be colorized toa color pattern of the color induction film 9. As a result, even thoughthe lower display module 2 receives the white rays, it can display thecorresponding information in colors.

[0058] Similarly to the scattering film 4, the transparent colorinduction film 9 can be lightly placed on the lower surface of the lightguide panel 3 by an insert molding process, or can be directly printedon the lower display module 2 by a printing process. It is to beappreciated that the transparent color induction film 9 may bepositioned on the lower surface of the light guide panel 3 in a varietyof ways depending upon a situation.

[0059] In a fourth embodiment of the present invention as shown in FIG.6, the scattering lines 4 a are directly formed on the lower surface ofthe light guide panel 3 and thereby obviates the need for the scatteringfilm 4.

[0060] Of course, in this case, since the scattering lines 4 a have afine line width in the range of 0.5˜5.5 μm, differently from theconventional reflective dots, to form an elongate mount structure, it ispossible to uniformly and distantly scatter and reflect an increasedamount of the light rays radiated from the two-way light sources 6toward the upper display module 1 when compared to the case of using theconventional reflective dots. Also, when compared to the conventionalart using the reflective dots, light rays having a significantlyimproved brightness are supplied to the upper display module 1.

[0061] Resultingly, in this fourth embodiment of the present invention,using the scattering lines 4 a, it is possible to improve a brightnessand brightness distribution uniformity of the light rays radiated fromthe two-way light sources 6 and supplied toward the upper display module1. Thus, a brightness requirement and a brightness distributionuniformity requirement under the color display mode can be properly met.

[0062] As apparent from the above description, the two-way display-typeliquid crystal display device according to the present inventionprovides advantages in that, since it has a part layout which enableslight rays radiated from one light source to simultaneously contributeto operation of upper and lower display modules, the number of lightsources is restrained from being unnecessarily increased, a weight and athickness of the liquid crystal display device are prevented from beingincreased, and assembly thereof is prevented from being complicated dueto provision of an additional light source.

[0063] Also, in the present invention, because it comprises a separatestructure such as, scattering film and scattering lines which have animproved light scattering function when compared to the conventionalreflective dots, a brightness of light rays radiated from a light sourceis increased, a requirement under a color display mode can be met, andbrightness distribution uniformity is improved.

[0064] The two-way display-type liquid crystal display device accordingto the present invention can be effectively applied to variouselectronic devices or instruments such as a notebook computer, a desktopcomputer, a mobile communication terminal, an electronic calculator, adigital camera, and so forth.

[0065] In the drawings and specification, there have been disclosedtypical preferred embodiments of the invention and, although specificterms are employed, they are used in a generic and descriptive senseonly and not for purposes of limitation, the scope of the inventionbeing set forth in the following claims.

What is claimed is:
 1. A two-way display-type liquid crystal displaydevice comprising: a pair of upper and lower display modules fordisplaying different information; a plurality of two-way light sourcesfor simultaneously supplying predetermined amounts of light rays to theupper and lower display modules; a light guide panel separately locatedat a side of the two-way light sources in a manner such that the upperand lower display modules are positioned on upper and lower surfaces ofthe light guide panel, respectively, the light guide panel functioningto guide light rays radiated from the two-way light sources in twodirections toward the upper and lower display modules; a scattering filminterposed between the light guide panel and the lower display module,for scattering and reflecting the light rays radiated from the two-waylight sources toward the upper display module; and a reflective andtransmissive sheet interposed between the light guide panel and thelower display module, for reflecting one part of the light rays radiatedfrom the two-way light sources toward the upper display module andtransmitting the other part of the light rays toward the lower displaymodule.
 2. The liquid crystal display device according to claim 1,wherein a plurality of transparent diffusion sheets are interposedbetween the light guide panel and the upper display module to diffusethe light rays radiated from the two-way light sources toward the upperdisplay module, each transparent diffusion sheet having grain which isformed to extend in a predetermined direction.
 3. The liquid crystaldisplay device according to claim 1, wherein a transparent colorinduction film is interposed between the light guide panel and the lowerdisplay module to colorize the light rays radiated from the two-waylight sources.
 4. The liquid crystal display device according to claim1, wherein an accommodating groove for accommodating the scattering filmand the reflective and transmissive film is formed on the lower surfaceof the light guide panel.
 5. The liquid crystal display device accordingto claim 1, wherein the scattering film is integrally attached to thelower surface of the light guide panel.
 6. The liquid crystal displaydevice according to claim 1, wherein a plurality of scattering lines areformed on a surface of the scattering film to linearly scatter the lightrays radiated from the two-way light sources.
 7. The liquid crystaldisplay device according to claim 6, wherein the scattering lines have aline width in the range of 0.5˜5.5 μm.
 8. A two-way display-type liquidcrystal display device comprising: a pair of upper and lower displaymodules for displaying different information; a plurality of two-waylight sources for simultaneously supplying predetermined amounts oflight rays to the upper and lower display modules; a light guide panelseparately located at a side of the two-way light sources in a mannersuch that the upper and lower display modules are positioned on upperand lower surfaces of the light guide panel, respectively, the lightguide panel functioning to guide light rays radiated from the two-waylight sources in two directions toward the upper and lower displaymodules, one surface of the light guide panel being directly formed witha plurality of scattering lines for linearly scattering and reflectingthe light rays radiated from the two-way light sources toward the upperdisplay module; and a reflective and transmissive sheet interposedbetween the light guide panel and the lower display module, forreflecting one part of the light rays radiated from the two-way lightsources toward the upper display module, and transmitting the other partof the light rays toward the lower display module.